When a communications device in existing Ethernet is in an application state, generally, transmission of port status information and control management information between a link layer (media access control (MAC)) device and a physical layer (PHY) device is implemented using a management data input/output (MDIO) interface, and service information is transmitted using a service (Ethernet (Eth)) interface between the MAC device and the PHY device. The PHY device includes a system side port and a line side port. The system side port is connected to the MAC device in order to implement the service interface between the MAC device and the PHY device, and the line side port of the PHY device is connected to a peer device in order to implement information transmission between the PHY device and the peer device.
An existing implementation manner for connecting an MDIO interface is as follows. The MAC device is connected to the PHY device using the MDIO interface. The MAC device acquires port status information on a line side and port status information on a system side of the PHY device. The MAC device is connected to an external processor using a control management interface such that the MAC device transmits the port status information on the PHY line side and the port status information on the PHY system side of the PHY device to the external processor, and the external processor delivers an instruction to the MAC device in order to perform configuration management on the PHY device using the MDIO interface between the MAC device and the PHY device, thereby controlling status synchronization between the system side port and the line side port of the PHY device. In an apparatus that implements a connection of such an MDIO interface, the PHY device and the MAC device are disposed on different physical boards. Because quantities of PHY devices and MAC devices that are disposed on each physical board are relatively large, a same quantity of MDIO interfaces as that of the PHY devices or the MAC devices need to be disposed on a backplane to implement a connection of MDIO interfaces between the PHY devices and the MAC devices, thereby consuming a large quantity of hardware resources and wasting space for backplane cabling.
In another existing implementation method for connecting a management data interface, a system device management module independent of an external processor is disposed such that a quantity of information transmission paths is relatively large, a signal connection is complex and troublesome, thereby increasing a communications node, further increasing a processing delay of a signal, and reducing reliability of communication between a link layer and a physical layer.